As informatization advances, a communication tool such as e-mail becomes necessary for our daily life. Communication through a telephone is immediate and can convey the feeling of an information sender, but constrains the receiver to a call. Meanwhile, although communication through e-mail has limitations about conveying the feeling, information can be sent and received in a short time, and has an advantage of no need to worry about the receiver's inconvenience, unlike communication through a telephone.
However, in interaction through these communication tools, there may be inconvenience since it cannot be known whether a receiver can communicate now or wants to communicate later. In addition, where an information receiver forgets to respond due to mixture in a large amount of information, it may be difficult for an information sender to determine to resend information since the information sender cannot grasp in which situation the information receiver is in: having failed in passing, issuing or sending a message, being unable to respond, forgetting to respond, or the like.
With respect to forgetting to reply to an e-mail, Patent Literature 1 discloses an art to extract an unanswered e-mail; Patent Literature 2 discloses an art to previously set whether an e-mail needs to be replied to or not; and Patent Literature 3 discloses a system to set a reply alarm to an e-mail that needs to be replied to, thereby performing notification.
Patent Literature 7 discloses an art to store a schedule that urges to respond to a received e-mail, to generate a notification mail on the basis of the stored schedule, to receive the notification mail in a pseudo manner, and to store the received notification mail as an e-mail.
Patent Literature 8 discloses an e-mail processing support device configured to analyze an e-mail by using a basic dictionary and user dictionary and to find the sum of priority points. This enables the e-mail processing support device disclosed in Patent Literature 8 to display the order of processing of e-mails in a list in order of priority or in order of tasks to be processed or in a calendar.
Patent Literature 4 discloses an art to search, data that is expected to be required by a user, from status data and an important word, on the basis of a status of the user and change of the status. Patent Literature 5 discloses an art to use a general-purpose formula for analyzing performance thereby to predict a web page access response time distribution in a plurality of assumed network. Patent Literature 6 discloses an information distribution method: including deciding order to distribute information to users on the basis of response time until an access destination specified by address information receives an access from a user; and distributing an e-mail to users according to the decided order to distribute.